Nearly a third of all bowel cancer cases could be inherited, say researchers.

Scientists said this could lead to a test to identify the people most at risk from the disease and improve their chances of early diagnosis and treatment.

The Cancer Research Campaign (CRC) funded team found that 30% of people with bowel cancer appeared to have an inherited problem with repairing their genes - compared to just 9% of the general population.

Cancer develops after cells suffer damage to their genes causing them to divide out of control and eventually form tumours.

This is important, because when doctors detect bowel cancer early, they have a good chance of curing the disease

Dr David Scott, of Christie Hospital, Manchester

Scientists think that people with defects in their system could be more likely to develop bowel cancer.

The team, based at the Paterson Institute in Manchester's Christie Hospital, took blood samples from 66 healthy people and 37 with bowel cancer.

They exposed their blood cells to radiation, which caused genetic damage and then examined them to see how well the cells repaired themselves.

Screening

They found that cells from healthy people generally recovered well from the radiation damage, but those with bowel cancer did not.

Dr David Scott, who led the study, said they could now use the information to identify and treat people at risk.

"If we can identify those people who are most likely to develop bowel cancer, we can screen them regularly, giving us a much better chance of detecting the disease early.

"This is important, because when doctors detect bowel cancer early, they have a good chance of curing the disease.

"But catch it late, and treatment is much less likely to be successful."

The research, published in the British Journal of Cancer, is announced to coincide with the launch of the CRC's Bowel Cancer Awareness month in April.

Bowel cancer is the third most common cancer in the UK, but the second biggest cause of cancer deaths.

In 1996, there were 34,384 cases, evenly split between men and women. There were just over 17,000 deaths in 1998.

Further tests

Professor Gordon McVie, director general of the CRC said: "Dr Scott's work is exciting because it has exposed one of the ways that bowel cancer might more easily develop.

"It may not be long before we are able to identify people at increased risk from the disease and give them regular screening, which might save many lives."

Dr Scott and his team found similar results for people with breast cancer and showed that in this case the defects in repairing radiation damage were inherited because they were shared by the relatives of patients.

They now want to do similar family tests into bowel cancer.

The CRC is currently conducting clinical trials of aspiring and folic acid supplements to see if these help prevent bowel cancer from recurring.

Eating lots of fruit and vegetables and cutting down on red meat is also though to help reduce rates of bowel cancer

Professor John Burn, head of Imperial Cancer Research Fund's Clinical Cancer Genetics network said the new research could help improve treatment for bowel cancer, allowing treatment to be better tailored to individual patients.